Bomb stabilizer



Jan. 29, 1946. w. F. BERGER BOMB S TABILI ZER :Filed Feb. 10. 194s l l a alla gmc/who@ William FI .Eerder www atented Jan. 29, 1946 UNITED STATS am OFFICE Application February 10,

1 Claim.

(Granted under the amended April 30, 1928;

The invention described herein may be manuactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon. n

This invention relates to means for improving the ballistic performance of elongated, symmetrical bombs or missiles dropped or projected from aircraft, or projected from smooth bore, unrifled, weapons, the chief object of the invention 'being to improve the stability of such bombs as will be explained with the aid of the accompanying sheet1 of drawings, wherein:

Fig. 1 represents a bomb provided with the improved stabilizer of this invention, in perfect vertical stabilization;

Fig. 2 shows the same bomb turned from its true trajectory due to influences which the improved stabilizer is designed to rectify.

Fig. 3 is an end view of one form of the improved stabilizer;

Fig. 4 is a side view of the improved stabilizer of the radial type, and

Fig. 5 is an end view of Fig. 4.

. A bomb or other missile is said to be fully stable in iiight when its longitudinal axis is tangent to its trajectory (the path of motion of its center of gravity); in the case of a vertically-falling bomb, whose trajectory is perpendicular to the horizon, the longitudinal axis would be coincident with the said perpendicular. This is the condition of the bomb shown in Fig. 1 wherein the center of gravity is designated I0.

Various factors and conditions such as the relative air flow passed the bomb, cross-winds, eddy currents, different atmospheric conditions such as air temperatures, unevenness of the bomb surface, lack of symmetry in its shape or weight distribution, etc., tend to cause the bomb to turn on its center of gravity, which continues on the perpendicular trajectory, various angular amounts depending upon the magnitude of such disturbing forces. The bomb is shown in Fig. 2 in this unstable condition, having been turned, by said forces, on its center of gravity through the angle shown (the angle of yaw, the turning of bomb being known as yawing).

My improved device makes use of the very factors (partially listed above) which disturb the stable night of the bomb or elongated projectile, to return the bomb or elongated projectile to stabilized condition. For this purpose I attach at the rear or tail end of the bomb or elongated projectile a stabilizer 20 in the form of a short tubular member spaced to provide a clearance A. The tubular stabilizer 20 may be held by a number of radial fins 2| extending from a ring 22 of the improved stabilizer secured on the tail end l2 of the bomb.

1943, Serial No. 475,341

act of March 3, 1883, as

The tubular stabilizer 2l) has, at all pointsbeing, in fact, a figure of revolutionan airfoil cross section, similar to the cross section of an airplane wing. In the stable condition of the bomb (Fig. 1) the chord a/-b of the airfoil stabilizer 20 is parallel to the direction of relative airflow, i, e., the angle of attack (between the chord and the relative airflow) is zero. However, in the unstable condition (Fig. 2) the chord makes an angle of attack (s) with the relative airflow resulting in the creation of a drag (D) and a lift (L). The latter force, which is at a lever arm (m) from the center of gravity l0, creates a torque (of magnitude, LXm) about the said point in a direction (clockwise, in Fig. 2) tending to bring the bomb back to stable position (perpendicular, Fig. l) As the bomb approaches the vertical, stable position, the angle of attack decreases; hence the torque tending to continue its turning also decreases. As a result the bomb will seek the vertical position as the point of equilibrium,

The improved stabilizer may comprise a tubular member 20, Figs. 1, 2, which may be of circular, square or irregular shape.

A square-shaped tubular member 30 is shown in Fig. 3, held in place by radial ns 3l extending from tail ring 32.

The improved stabilizer'of Figs. 1 to 3 are polygonal figures of revolution. The principle of the invention is applied to stabilization of the radial type in Figs. 4, 5 where the radial lns 40 have airfoil cross sections, and extend from the tail ring 42. While four radial fins are shown in Figs. 4, 5, it is clear that the invention is equally adapted to three or more radial ns.

\ I claim:

In a device for stabilizing the flight of an elongated missile having a reduced tail end by maintaining the longitudinal axis tangent to the trajectory traced by the center of gravity, said missile having radiating fins attached to its tail end, arcuate stabilizers connecting said ns, said stabilizers being tapered in longitudinal crosssection and positioned with blunt ends toward the front end of themissile and having a camber comprising convex surfaces facing said reduced tail portion of the missile and concave surfaces facing away from said reduced portion, said stabilizer presenting an angle of attack with the axis of the missile and beingadapted to coact in ght with the air flow through the fins and ,create a torque tending to turn the tail end of the missile in a direction to decrease the angle of yaw from the trajectory to bring the longitudinal axis of the missile into coincidence with said trajectory.

WILLIAM F. BERGER. 

